Pyridine → 6-Bromo-(1,2,4)triazolo(1,5-a)pyridine

To an ice-cooled, stirred solution of the crude product from Step A (3.94 g, 17.3 mmol) in methanol (30 mL) and pyridine (2.73 g, 35.6 mmol) was added hydroxylamine-O-sulfonic acid (2.54 g, 22.5 mmol). The reaction mixture was allowed to warm to room temperature and was stirred overnight. The volatiles were removed under reduced pressure, and the residue was partitioned between aqueous sodium bicarbonate solution and ethyl acetate. The aqueous layer was further extracted with ethyl acetate, and the combined organic layers were washed sequentially with water (100 mL) and saturated aqueous brine solution (100 mL), dried (magnesium sulfate) and concentrated in vacuo to yield a brown solid, which was recrystallized from dichloromethane to afford the title compound as an orange solid. LC/MS 197.9 and 199.9 (M+1).